Manufacturing methods and surface treatment solutions for glass cloth, prepreg, printed wiring boards, integrated circuits, electronic devices, and glass cloth.

Abstract

The objective of this invention is to provide a glass cloth with excellent dielectric properties that can suppress the increase of dielectric loss factor over time. The glass cloth of the present invention is constructed by using glass yarn containing a plurality of glass filaments as warp and weft yarns. The glass cloth has a surface treatment agent on its surface, the surface treatment agent containing a silane coupling agent having a molecular structure with a value of 15.0 or less obtained from the following formula: 1.10×MaxEStateIndex+14.6×MaxPartialCharge-0.0917×SPS+2.47×HallKierAlpha.

Description

[Technical Field]

[0001] This invention relates to a glass cloth, a prepreg, a printed wiring board, and a surface treatment liquid, etc. [Previous Technology]

[0002] Currently, the high performance of information terminals such as smartphones and the high speed of communication represented by 5G are developing. Along with this, in printed circuit boards used for high-speed communication, there is a significant development in the reduction of dielectric constant and dielectric loss factor of insulating materials used to reduce transmission loss. In addition, there is a demand for insulation reliability that is higher than before.

[0003] Examples of insulating materials for printed wiring boards for high-speed communications are reported in Patent Documents 1 and 2. Specifically, in Patent Documents 1 and 2, a low-dielectric thermosetting resin (hereinafter collectively referred to as "matrix resin") that is cross-linked by a free radical reaction to a polyphenylene ether or the like, which is terminally modified with vinyl or methacryloxy groups, is impregnated with glass cloth and dried to obtain a prepreg. It is known to obtain a laminate by heating and pressurizing the prepreg volume layer thus obtained. The object of Patent Documents 1 and 2 is to obtain a laminate having a low dielectric constant and a low dielectric loss factor using glass cloth with a low dielectric constant and a low dielectric loss factor.

[0004] Here, to reduce the dielectric loss factor of glass cloth, Patent Documents 3 and 4 describe reducing the amount of silanol groups on the glass surface by heating the silica glass cloth at high temperature. Patent Document 5 describes reducing the amount of silanol groups present on the surface of the glass cloth through surface treatment, thereby reducing the dielectric loss factor of the glass cloth. Patent Document 6 describes a packaging method for quartz glass cloth to suppress the over-time increase of the dielectric loss factor of quartz glass cloth. [Prior Art Documents] [Patent Documents]

[0005] [Patent Document 1] International Publication No. 2019 / 065940 [Patent Document 2] International Publication No. 2019 / 065941 [Patent Document 3] Japanese Patent Application Publication No. 2021-63320 [Patent Document 4] Japanese Patent Application Publication No. 2021-195689 [Patent Document 5] Japanese Patent Application Publication No. 2020-194888 [Patent Document 6] Japanese Patent No. 7375902 [Summary of the Invention]

[0006] [Problem to be Solved by the Invention] One object of the present invention is to provide a glass cloth with excellent dielectric properties, capable of suppressing the increase of dielectric loss factor over time. Another object is to provide a method for manufacturing the aforementioned glass cloth, and a surface treatment liquid used in the aforementioned glass cloth. Furthermore, an object of the present invention is to provide a prepreg and a printed wiring board using the aforementioned glass cloth. [Technical Means for Solving the Problem]

[0007] Examples of embodiments of the present invention are listed in the following items [1] to

[38] . [1] A glass cloth, which is composed of glass yarn containing a plurality of glass filaments as warp and weft yarns, and the glass cloth has a surface treatment agent on its surface, the surface treatment agent containing a silane coupling agent having a molecular structure having a value of 15.0 or less obtained from the following formula (A): 1.10×MaxEStateIndex+14.6×MaxPartialCharge-0.0917×SPS+2.47×HallKierAlpha・・・(A) [2] The glass cloth of item 1, wherein the number of white spots is 10 or less per m2. [3] The glass cloth of item 1 or 2, wherein the silicon (Si) content in the glass yarn is 95.0 to 100% by mass when converted to silicon dioxide (SiO2). [4] The glass cloth of any one of items 1 to 3, wherein the silane coupling agent contains a silane coupling agent represented by the following general formula (1): X4-n-Si-Yn・・・(1) (in formula (1), X is an organic functional group having at least one of epoxy group, amino group, and unsaturated double bond group having free radical reactivity, Y is an alkoxy group, and n is an integer from 1 to 3). [5] The glass cloth of item 4, wherein X in the above general formula (1) contains at least one group selected from the group consisting of epoxy group, amino group, aromatic vinyl group, acrylonitrile group, and methacrylonitrile group. [6] The glass cloth of any one of items 1 to 5, wherein the dielectric loss factor of the glass cloth at 10 GHz is 0.002 or less. [7] The glass cloth of any one of items 1 to 6, wherein the loss on ignition value is in the range of 0.01 to 0.3% by mass. [8] For any of the glass cloths in items 1 to 7, the value obtained from formula (A) above is 14.4 or less. [9] For any of the glass cloths in items 1 to 8, the value obtained from formula (A) above is 13.8 or less.

[10] For any of the glass cloths in items 1 to 9, the value obtained from formula (A) above is 13.5 or less.

[11] For any of the glass cloths in items 1 to 10, the number of white spots is 4 or less per m2.

[12] For any of the glass cloths in items 1 to 11, the number of white spots is 2 or less per m2.

[13] For any of the glass cloths in items 1 to 12, the number of white spots is 0.1 or less per m2.

[14] For any of the glass cloths in items 1 to 13, the number of white spots is 0.05 or less per m2.

[15] The glass cloth of any one of items 1 to 14, wherein the molecular weight of the silane coupling agent is in the range of 250 to 1000.

[16] The glass cloth of any one of items 1 to 15, wherein the molecular weight of the silane coupling agent is in the range of 300 to 750.

[17] The glass cloth of any one of items 1 to 16, wherein the molecular weight of the silane coupling agent is in the range of 350 to 700.

[18] The glass cloth of any one of items 1 to 17, which is for use in printed wiring boards.

[19] A prepreg comprising the glass cloth of any one of items 1 to 18, a matrix resin, and an inorganic filler.

[20] A printed wiring board comprising the prepreg of item 19.

[21] An integrated circuit comprising the printed wiring board of item 20.

[22] An electronic device comprising the printed wiring board of item 20.

[23] A method for manufacturing glass cloth, the method comprising: weaving glass yarn containing a plurality of glass filaments as warp and weft yarns to obtain glass cloth; and subjecting the glass cloth to degreasing treatment and then surface treatment with a surface treatment liquid containing a surface treatment agent; wherein the surface treatment agent contains a silane coupling agent having a molecular structure having a value of 15.0 or less obtained from the following formula (A): 1.10×MaxEStateIndex+14.6×MaxPartialCharge-0.0917×SPS+2.47×HallKierAlpha・・・(A)

[24] The method for manufacturing glass cloth according to item 23, wherein the silane coupling agent contains the following general formula (1): X4-n-Si-Yn・・・(1) (in formula (1), X is an organic functional group having at least one of an epoxy group, an amino group, and an unsaturated double bond group having free radical reactivity, Y is an alkoxy group, and n is an integer from 1 to 3).

[25] The method for manufacturing glass cloth according to item 23 or 24, wherein the surface treatment liquid is prepared by adding an acidic aqueous solution to the hydrolysis solution of the silane coupling agent.

[26] The method for manufacturing glass cloth according to any one of items 23 to 25, wherein the surface treatment step includes: controlling the temperature and pH value of the surface treatment liquid; and filtering the surface treatment liquid.

[27] The method for manufacturing glass cloth according to any one of items 23 to 26, further includes: after the surface treatment step, performing a fiber opening treatment on the glass cloth.

[28] The method for manufacturing glass cloth according to any one of items 23 to 27 further includes: a step of checking for white spots after the above-mentioned surface treatment step.

[29] A surface treatment liquid comprising a surface treatment agent containing a silane coupling agent, wherein the silane coupling agent has a molecular structure with a value of 15.0 or less obtained from the following formula (A): 1.10×MaxEStateIndex+14.6×MaxPartialCharge-0.0917×SPS+2.47×HallKierAlpha・・・(A)

[30] The surface treatment solution of Item 29, wherein the surface treatment solution contains a silane coupling agent in the range of 0.20 to 1.2% by mass based on the total mass of the surface treatment solution, the pH value of the surface treatment solution is in the range of 2.5 to 5.5, and the surface treatment solution contains a surfactant in the range of 0.5 to 5.0% by mass based on the total mass of the silane coupling agent.

[31] The surface treatment solution of Item 29 or 30, wherein the silane coupling agent contains the following general formula (1): X4-n-Si-Yn・・・(1) (in formula (1), X is an organic functional group having at least one of an epoxy group, an amino group, and an unsaturated double bond group having free radical reactivity, Y is an alkoxy group, and n is an integer from 1 to 3).

[32] The surface treatment solution of any one of items 29 to 31, wherein the value obtained from formula (A) above is 14.4 or less.

[33] The surface treatment solution of any one of items 29 to 32, wherein the value obtained from formula (A) above is 13.8 or less.

[34] The surface treatment solution of any one of items 29 to 33, wherein the value obtained from formula (A) above is 13.5 or less.

[35] The surface treatment solution of any one of items 29 to 34, wherein the pH value of the surface treatment solution is in the range of 3.0 to 5.0.

[36] The surface treatment solution of any one of items 29 to 35, wherein the pH value of the surface treatment solution is in the range of 3.0 to 4.0.

[37] The surface treatment solution of any one of items 29 to 36, wherein the surface treatment solution contains a surfactant in the range of 1.0 to 4.5% by mass based on the total mass of the silane coupling agent.

[38] The surface treatment liquid of any one of items 29 to 37, wherein the surface treatment liquid contains a surfactant in the range of 1.5 to 4.0% by mass based on the total mass of the silane coupling agent. [Effects of the invention].

[0008] According to the present invention, a glass cloth having excellent dielectric properties and capable of suppressing the increase of dielectric loss factor over time can be provided. Furthermore, a method for manufacturing the aforementioned glass cloth and a surface treatment liquid used in the aforementioned glass cloth can be provided. Moreover, the present invention can provide a prepreg using the aforementioned glass cloth and a printed wiring board, etc.

Implementation Method

[0010] Hereinafter, embodiments of the present invention will be described. However, the present invention is not limited to these embodiments, and various changes can be made without departing from its spirit.

[0011] In this specification, when multiple structures represented by the same symbol exist in the same formula, unless otherwise specified, each structure can be selected independently, and they can be the same or different from each other. Similarly, when multiple structures represented by the same symbol exist in different formulas, unless otherwise specified, each structure can be selected independently, and they can be the same or different from each other. In this specification, all measurements are performed based on the methods described in the embodiments unless otherwise specified. In this specification, the upper or lower limit of the numerical range described in stages can be replaced with the corresponding upper or lower limit of the numerical range described in other stages, and further, can be replaced with the corresponding values ​​described in the embodiments.

[0012] In this specification, the term "step" is not limited to independent steps; even steps that cannot be clearly distinguished from other steps are included in this terminology as long as they achieve the function of the step. In the drawings, scale, shape, and length are exaggerated for the sake of clarity.

[0013] <<Glass Cloth>> The glass cloth of the present invention is a glass cloth woven from glass yarn, for example, a glass cloth composed of glass yarn containing a plurality of glass filaments as warp and weft yarns. The surface of the glass cloth has a surface treatment agent, and the silane coupling agent contained in the surface treatment agent has a molecular structure with a value of 15.0 or less obtained from the following formula (A). 1.10×MaxEStateIndex+14.6×MaxPartialCharge-0.0917×SPS+2.47×HallKierAlpha・・・(A)

[0014] According to the present invention, a glass cloth with excellent dielectric properties is provided, which can suppress the increase of dielectric loss factor over time. The glass cloth of the present invention is suitable as a constituent material for manufacturing prepregs, printed wiring boards, integrated circuits, and electronic devices. Preferably, compared with the prior art described in Patent Documents 1 to 6, the dielectric loss factor of the glass cloth can be further reduced. Furthermore, it is preferable that the method of packaging quartz glass cloth in a specified manner as described in Patent Document 6 is not used, and the increase of dielectric loss factor of the glass cloth over time can be suppressed.

[0015] Through dedicated research, the inventors of this invention have focused on glass cloth that has undergone surface treatment after being degreased by heating at high temperatures. The inventors of this invention have discovered for the first time that glass cloth that has undergone surface treatment with a silane coupling agent having a molecular structure with a value of 15.0 or less obtained from the above formula (A) after being degreased by heating at high temperatures exhibits a lower dielectric loss factor and can suppress the increase in dielectric loss factor over time. The reason for this is not limited to theory, but it is considered that by coating the surface of the glass cloth with the silane coupling agent, it is less likely to absorb moisture present in the storage environment. Therefore, even without special packaging, the increase in dielectric loss factor of the glass cloth over time can be suppressed. The technical significance of each parameter will be described below.

[0016] Silicon coupling agents are typically used in glass cloth as mixtures with solvents. In this case, from the viewpoint of reducing environmental impact, water is preferred as the solvent. However, it is known that silicon coupling agents with a value of 15.0 or less obtained from formula (A) are more hydrophobic and have significantly poorer dispersibility and / or compatibility with water. Therefore, the surface of the glass cloth is prone to "white spots" caused by surface treatment agents. White spots can sometimes hinder the adhesion between the glass cloth and the resin interface. Therefore, it is preferable to provide a glass cloth that suppresses white spots and has a lower dielectric loss factor than bulk glass.

[0017] According to a preferred embodiment of the present invention, even surface treatment agents with poor dispersibility and / or miscibility with water, i.e., those with strong hydrophobicity (e.g., strong hydrophobic silane coupling agents), can suppress white spots by being stably dispersed in water. In this case, it is easy to provide glass cloth with a lower dielectric loss factor, and even without special packaging, it is easier to suppress the increase in the dielectric loss factor of the glass cloth over time. Furthermore, it is easy to provide glass cloth that can provide resin substrates with excellent solder heat resistance.

[0018] [Dielectric Loss Factor] (Dielectric Loss Factor of Glass Cloth) The dielectric loss factor of the glass cloth of the present invention at 10 GHz is preferably 0.0020 or less. With such a glass cloth, a prepreg and printed wiring board with improved dielectric properties can be provided. From the viewpoint of improving dielectric properties, the dielectric loss factor of the glass cloth at 10 GHz is preferably 0.0015 or less, 0.0010 or less, 0.0007 or less, 0.0006 or less, 0.0005 or less, 0.0004 or less, 0.0003 or less, or 0.0002 or less. The dielectric loss factor of the glass cloth can exceed 0.

[0019] (Method for Measuring the Dielectric Loss Factor of Glass Cloth) Regarding the glass cloth of the present invention, the dielectric loss factor at 10 GHz is measured by using a split-cylinder resonator (a method using the resonance method), specifically, by the method described in the embodiments. According to this method, compared with previous measurement methods for evaluating dielectric properties by fabricating a substrate as a test sample, it is easier, simpler, and more accurate to perform the measurement. The reason for this is not limited to theory, but the resonance method is suitable for evaluation in the high-frequency region, and is particularly suitable for evaluating low-loss materials. As a method for evaluating dielectric properties other than the resonance method, lumped parameter method and reflection transmission method are known, for example. However, in the lumped parameter method, the test sample must be clamped with two electrodes to form a capacitor, which makes the operation cumbersome. In addition, in the reflection transmission method, when evaluating low-loss materials, the effect of port matching characteristics is strongly manifested, which makes it difficult to evaluate the dielectric loss factor of the test sample with high accuracy. Based on the above, the method described in the embodiments, specifically, based on the use of resonance, makes it easy, simple, and highly accurate to measure the dielectric loss factor of glass cloth.

[0020] Regarding the glass cloth used in printed wiring boards, especially the glass cloth used in printed wiring boards for high-speed communications, the measuring machine used to determine its dielectric properties preferably has a specified measurable range. For example, regarding the dielectric constant (Dk) and dielectric loss factor (Df), the measuring machine preferably has a measurable range of Dk = 1.1 to 50 and Df = 1.0 × 10⁻⁶ to 1.0 × 10⁻¹, more preferably a measurable range of Dk = 1.5 to 10 and Df = 1.0 × 10⁻⁵ to 5.0 × 10⁻¹, and even more preferably a measurable range of Dk = 2.0 to 5 and Df = 5.0 × 10⁻⁵ to 1.0 × 10⁻².

[0021] Furthermore, the measuring machine used to determine dielectric properties is preferably capable of measuring frequencies of 10 GHz or higher. If the measurable frequency is 10 GHz or higher, it is easier to evaluate the characteristics in the frequency band, especially the assumed characteristics in the case of glass cloth used in printed wiring boards for high-speed communications.

[0022] The area for measuring dielectric properties is preferably 10 mm² or more, more preferably 15 mm² or more, and even more preferably 20 mm² or more. This makes it easier to improve the reliability of the obtained measurement results, and thus makes it easier to determine whether the obtained measurement results are within the range of the preset reference values.

[0023] The thickness of the sample is preferably 3 μm to 300 μm, more preferably 5 μm to 200 μm, and even more preferably 7 μm to 150 μm.

[0024] (Bulk Dielectric Loss Factor) In the glass cloth of the present invention, the bulk dielectric loss factor of the glass raw material constituting the glass cloth at 10 GHz is measured by a method using a split cylindrical resonator (a method using resonance), specifically, by the method described in the embodiments. Here, the glass raw material may be, for example, glass yarn, glass filament, and glass type.

[0025] The bulk dielectric loss factor at 10 GHz is preferably 0.002 or less, more preferably 0.0015 or less, even more preferably 0.001 or less, even more preferably 0.0005 or less, and particularly preferably 0.0004 or less. This makes it easier to achieve excellent dielectric properties.

[0026] [Glass yarn] Glass yarn may contain multiple glass filaments. Glass cloth can be made by weaving glass yarn as both warp and weft yarns.

[0027] [Average filament diameter] The average filament diameter of the glass filament is preferably 2.5 μm to 9.0 μm, more preferably 2.5 μm to 7.5 μm, even more preferably 3.5 μm to 7.0 μm, even more preferably 3.5 μm to 6.0 μm, and particularly preferably 3.5 μm to 5.0 μm.

[0028] [Weaving density] The weaving density of the glass yarn (warp and weft) constituting the glass cloth is preferably 10 to 120 yarns / inch (= 10 to 120 yarns / 25.4 mm), more preferably 40 to 100 yarns / inch, and even more preferably 45 to 90 yarns / inch.

[0029] [Weight per unit area] The weight per unit area of ​​the glass cloth is preferably 8 to 250 g / m2, more preferably 8 to 100 g / m2, even more preferably 8 to 80 g / m2, and even more preferably 8 to 50 g / m2.

[0030] [Glass Type] Previously, the glass cloth used in prepregs (laminated sheets) typically used glass raw materials known as E glass (alkali-free glass). On the other hand, the glass cloth of the present invention can use glass raw materials such as L glass, NE glass, D glass, L2 glass, T glass, silica glass, and quartz glass. From the viewpoint of excellent dielectric properties, it is preferable to use glass raw materials such as L glass, L2 glass, silica glass, and quartz glass, among which silica glass and quartz glass are particularly preferred. Furthermore, from the viewpoint of improving the dimensional stability of the laminate containing the glass cloth, it is preferable to use glass raw materials such as S glass, T glass, silica glass, and quartz glass, among which silica glass and quartz glass are particularly preferred.

[0031] In the glass yarn constituting the glass cloth, the silicon (Si) content, calculated as silicon dioxide (SiO2), is preferably 95.0–100% by mass or 99.0–100% by mass, more preferably 99.5–100% by mass, and even more preferably 99.9–100% by mass. The SiO2 content of the glass yarn constituting the glass cloth is particularly preferably greater than 99.9% by mass. If the Si content is 95.0% by mass or more, it is easier to ensure the dielectric properties of the glass cloth and the dimensional stability of the laminate.

[0032] [Weaving Structure] Examples of weaving structures for glass cloth include plain weave, square plain weave, satin weave, and twill weave, with plain weave being the most preferred.

[0033] [Surface Treatment Agent] The glass cloth has a surface treatment agent on its surface. The surface treatment is performed, for example, by using a surface treatment liquid containing a surface treatment agent. Details are described below.

[0034] Previously, it was recognized that if conventional surface treatment agents (such as conventional silane coupling agents) were used, the dielectric loss factor of the glass cloth would increase due to the surface treatment, and the dielectric loss factor of the glass cloth would increase over time. In this regard, the inventors of this invention conducted research and found that by surface treating the glass surface with a more hydrophobic surface treatment agent (such as a more hydrophobic silane coupling agent), the increase in the dielectric loss factor of the glass cloth caused by the surface treatment could be reduced. Furthermore, moisture present in the storage environment was less likely to be adsorbed onto the glass surface. As a result, even without a special moisture-proof packaging, the increase in the dielectric loss factor of the glass cloth over time was easily suppressed.

[0035] In this invention, "a surface treatment agent with strong hydrophobicity (a silane coupling agent with strong hydrophobicity)" refers to a state in which the surface treatment agent (silane coupling agent) is not uniformly dispersed as an emulsion in the aqueous solution or is in an undissolved state when an aqueous solution containing 0.3% by mass of acetic acid is stirred at room temperature (25°C) for 3 hours.

[0036] (Silane Coupling Agent) In this invention, the surface treatment agent preferably contains a silane coupling agent. That is, the glass yarn (containing glass filaments) constituting the glass cloth is preferably surface treated by a silane coupling agent.

[0037] The glass cloth of the present invention is surface-treated using a silane coupling agent with a value of 15.0 or less obtained from the following formula (A). 1.10×MaxEStateIndex+14.6×MaxPartialCharge-0.0917×SPS+2.47×HallKierAlpha・・・(A)

[0038] MaxEStateIndex, MaxPartialCharge, SPS, and HallKierAlpha contained in formula (A) can be obtained by the method described in the embodiments. Specifically, they can be obtained by using open-source software called "RDKit".

[0039] The MaxEStateIndex used in Formula (A) is a value representing the electronic properties of an atom, calculated based on the atomic charge or the number of bonds. Generally speaking, it is believed that if the MaxEStateIndex value of an atom is higher, the polarity of the molecule or its hydrogen bonding ability is higher. Furthermore, MaxPartialCharge represents the partial charge of the molecule; it is believed that the larger the value, the larger the dipole moment within the molecule, and the easier it is to polarize. To easily obtain excellent dielectric properties and suppress the increase in dielectric loss factor over time, the values ​​of MaxEStateIndex and MaxPartialCharge should be as low as possible. This is because the more strongly polarized the silane coupling agent coated glass cloth is, the more easily it absorbs moisture from the air. Without special packaging, it is difficult to suppress the increase in the dielectric loss factor of the glass cloth over time.

[0040] Furthermore, the SPS used in formula (A) is an empirical scoring system used to represent the spatial complexity of compounds in a uniform manner, at a highly granular scale for intermolecular ordering and comparison. A higher value indicates less steric hindrance. Also, HallKierAlpha is a topological index representing the steric hindrance of molecules; a higher value indicates higher steric hindrance. Based on these results, treating the glass cloth surface with a silane coupling agent with higher steric hindrance shows a tendency to more readily adsorb moisture from the air. This is because a higher steric hindrance silane coupling agent is more difficult to uniformly chemically modify the glass surface, and the silane coupling agent layer tends to be sparse, thus easily adsorbing moisture from the air and causing the dielectric loss factor of the glass cloth to increase over time.

[0041] From the viewpoint of easily obtaining excellent dielectric properties and suppressing the increase of dielectric loss factor over time, the value obtained from formula (A) is preferably 14.9 or less, more preferably 14.8 or less, further preferably 14.7 or less, further preferably 14.6 or less, and even more preferably 14.4 or less, 14.2 or less, 14.0 or less, or 13.8 or less. The lower limit of the value obtained from formula (A) is not particularly limited and may be greater than 0, greater than 1, greater than 5, or greater than 10.

[0042] The surface treatment agent is preferably, for example, a silane coupling agent represented by the following formula (1): X4-n-Si-Yn・・・(1) (in formula (1), each X is an organic functional group having at least one of an epoxy group, an amino group, and an unsaturated double bond group having free radical reactivity, each Y is an alkoxy group, and n is an integer from 1 to 3). By including the silane coupling agent in the surface treatment agent, it is easier to suppress the increase in the dielectric loss factor of the glass cloth over time.

[0043] As X in formula (1), from the viewpoint of easily improving adhesion to the resin, it is more preferably an organic functional group having at least one group selected from the group consisting of epoxy, amino, aromatic vinyl, acrylonitrile, and methacrylonitrile in its structure. Furthermore, the organic functional group is independently, for example, preferably an aromatic group and an aliphatic group that can be saturated or unsaturated, straight-chain or branched, having a cyclic structure or not, having heteroatoms or not; and at least one group selected from combinations thereof. The total number of carbons in X is preferably 3–20, 5–18, 6–16, or 7–14.

[0044] Regarding the above-mentioned Y, as an alkoxy group, from the viewpoint of the stability of the surface treatment of glass cloth, it is preferred to be an alkoxy group with 1 to 5 carbons (1, 2, 3, 4 or 5 carbons).

[0045] As a silane coupling agent contained in the surface treatment agent, one or more of the silane coupling agents shown in the above formula (1) may be used. For example, two or more of the above-mentioned different silane coupling agents may be used in combination.

[0046] As a silane coupling agent represented by general formula (1), examples include: 3,6-divinyl-1-(trimethoxysilyl)naphthalene, [Chemical 1] methyl 2-acrylate [4-[2-(trimethoxysilyl)ethyl]phenyl], [Chemical 2] 4-(trimethoxysilyl)phenyl acrylate, [Chemical 3] N-vinyl-N-(2-epoxyethoxy)-3-(trimethoxysilyl)-1-propylamine, [Chemical 4] 1-vinyl-4-[3-(trimethoxysilyl)propoxy]benzene, [Chemical 5] 4-[2-(trimethoxysilyl)ethyl]aniline. [Chemical 6] The following formula represents [bicyclo[2.2.1]hept-5-en-2-yl]triethoxysilane; [Chemical 7] The following formula represents 2-methyl-2-acrylate 4-[[4-[3-(trimethoxysilyl)propoxy]phenyl]sulfonyl]phenyl ester; [Chemical 8] The following formula represents 2-methyl-2-acrylate 6-[[[3-(trimethoxysilyl)propyl]amino]carbonyl]-2-naphthyl ester; [Chemical 9] The following formula represents 2-acrylate, 2-methyl-,2-[(trimethoxysilyl)methyl]-1,3-propanediyl ester; [Chemical 10] The following formula represents diethoxy(methyl)[2-(7-oxabicyclo[4.1.0]hept-3-yl)ethyl]silane; [Chemical 11] Ethoxy(dimethyl)[3-(ethyleneoxy-2-ylmethoxy)propyl]silane, [Chemical 12] [2-(bicyclo[2.2.1]hept-5-en-2-yl)ethyl](trimethoxy)silane, [Chemical 13] N-2-propen-1-yl-N-[3-(trimethoxysilyl)propyl]-2-ethyleneoxymethylamine, [Chemical 14] N1-vinyl-N1-(phenylmethyl)-N2-[3-(trimethoxysilyl)propyl]-1,2-ethanediamine, [Chemical 15] 2-methyl-2-acrylate 1-[trans-4-[4-(3-methylbutyl)phenyl]cyclohexyl]-2-(trimethoxysilyl)ethyl ester, [Chemical 16] etc.

[0047] The silane coupling agent that can be used can be appropriately adjusted according to the matrix resin used in the resin substrate. Of course, a silane coupling agent with a value of 15.0 or less obtained from formula (A) above can be used in combination with a silane coupling agent other than a silane coupling agent with a value of 15.0 or less obtained from formula (A) above. On the other hand, it is preferable to use two or more silane coupling agents with a value of 15.0 or less obtained from formula (A) above and different molecular weights. By using two or more silane coupling agents with different molecular weights, the density of the treatment agent on the glass surface is more likely to increase, and as a result, there is a tendency for the reactivity with the matrix resin to be further increased.

[0048] (Molecular weight of silane coupling agent) The molecular weight of the surface treatment agent, such as the silane coupling agent, is preferably 250-1000, more preferably 270-800, further preferably 300-750, and even more preferably 350-700. Furthermore, when using two or more surface treatment agents (e.g., silane coupling agents), it is preferable that the weighted average molecular weight obtained by weighting the mass of each surface treatment agent is within the above range, and more preferably that the total molecular weight of all the surface treatment agents used is within the above range. For example, when preparing surface treatment agents with molecular weights of 300 and 500 at 0.5% and 1.0% by mass, respectively, the weighted average can be calculated as follows. Weighted average = 300 × 0.5 ÷ (0.5 + 1.0) + 500 × 1.0 ÷ (0.5 + 1.0) = 433

[0049] [Average fiber openness of glass cloth] The average fiber openness of glass cloth is preferably 35% or more or more than 36%, more preferably more than 38%, and even more preferably more than 40%, more than 45%, more than 50%, more than 52% or more than 55%, and especially more than 57%. If the average fiber openness of glass cloth is 35% or more, it is easier to suppress air bubbles, which are called voids, in the fiber bundles of glass cloth when making resin substrates, thereby reducing the adverse effects on the heat resistance and insulation reliability of solder. Furthermore, as the silane coupling agent shown in the above formula (1), since the intermolecular forces are more likely to act strongly, the impregnation of the matrix resin of the glass cloth is more likely to become unfavorable compared with silane coupling agents other than those shown in the above formula (1). Therefore, from the viewpoint of fully achieving the effect of improving the insulation reliability of glass cloth surface treated with the silane coupling agent shown in formula (1), the average fiber opening degree is preferably 35% or more or greater than 36%. Furthermore, the upper limit of the average fiber opening degree is 85%. If the average fiber opening degree is to be set to 85% or more, it is necessary to strengthen the fiber opening treatment of the glass cloth, which can easily lead to a decrease in the fiber quality of the glass cloth.

[0050] [Loss on Ignition Value of Glass Cloth] From the viewpoint of easily reducing the dielectric loss factor of the glass cloth, the loss on ignition value of the glass cloth is preferably 0.01 to 0.3% by mass or 0.02 to 0.27% by mass, more preferably 0.03 to 0.24% by mass, further preferably 0.03 to 0.20% by mass, and even more preferably 0.03 to 0.17% by mass. If the loss on ignition value is 0.01% by mass or higher, it is easy to ensure the adhesion between the resin and the glass cloth in the obtained prepreg. In this case, it is easy to ensure heat resistance and insulation reliability when manufacturing printed wiring boards. If the loss on ignition value of the glass cloth is 0.3% by mass or lower, it is easy to avoid the presence of a large amount of surface treatment agent (or its residue) that does not form chemical bonds with the glass cloth surface but is physically attached, surface treatment agent (or its residue) that cannot be reduced from the glass cloth surface by water washing, and / or its modifiers. In this case, it is easy to achieve a low dielectric loss factor for the glass cloth.

[0051] [White Spots on Glass Cloth] Sometimes white spots are observed on the surface of surface-treated glass cloth. These white spots tend to repel the matrix resin used in the production of the prepreg, and therefore may cause poor appearance of the obtained prepreg. Previously, the cause of these white spots was unknown.

[0052] Regarding this aspect, the inventors of this invention have determined that one of the aforementioned white spots is an aggregate or a modified form of a surface treatment agent with strong hydrophobicity (e.g., a silane coupling agent with strong hydrophobicity). In particular, the inventors of this invention have determined that silane coupling agents with a value of 15.0 or less obtained from the above formula (A) have strong hydrophobicity, and therefore tend to easily generate aggregates. Furthermore, when the solvent of the surface treatment solution contains water, the frequency of white spot formation in the surface-treated glass cloth tends to increase (e.g., more than 10.0 spots / m2).

[0053] To suppress white spots, the following method is preferred: preparing a surface treatment solution by a specified method, managing the temperature and pH of the surface treatment solution, and removing precipitates from the surface treatment solution by filtering it.

[0054] The frequency of white spots in the glass cloth is preferably 10.0 spots / m² or less, more preferably 7.0 spots / m² or less, even more preferably 4.0 spots / m² or less, even more preferably 2.0 spots / m² or less, or 0.1 spots / m² or less, and particularly preferably 0.05 spots / m² or less. This facilitates the achievement of a prepreg with excellent appearance.

[0055] <<Method for Manufacturing Glass Cloth>> The present invention also provides a method for manufacturing the glass cloth of the present invention. The manufacturing method of the present invention includes the steps of: weaving glass yarn containing a plurality of glass filaments as warp and weft yarns to obtain glass cloth; and the steps of degreasing the glass cloth and then surface-treating the glass yarn with a surface-treating liquid containing a surface-treating agent. The surface-treating agent is the surface-treating agent of the present invention. Furthermore, the dielectric loss factor of the surface-treated glass cloth at 10 GHz is preferably lower than that of the surface-treated glass cloth at 10 GHz.

[0056] Here, the surface treatment step may further include one or more of the following steps: a step of reducing the fiber sizing agent adhering to the glass yarn by heating the glass yarn (heating degreasing step); a step of washing the glass yarn with water (washing step); and / or a step of opening the glass yarn (opening step).

[0057] The surface treatment step, fiber opening step, and washing step can be performed on the glass yarn before the step of weaving the glass yarn to obtain glass cloth (weaving step), or on the glass cloth after the weaving step. Furthermore, the order of the heating and degreasing step, surface treatment step, fiber opening step, and washing step can be interchanged, but the heating and degreasing step is performed before the surface treatment step. When the washing step is performed after the weaving step, it can also serve as the fiber opening step by using a high-pressure water jet or similar device. Moreover, the composition of the glass cloth usually remains unchanged before and after fiber opening.

[0058] [Heating Degreasing Step] In this step, by heating the glass yarn, the fiber binding agent (sizing agent), its residues, and modifiers adhering to the glass yarn can be reduced, and preferably removed. By performing the heating degreasing step, a surface treatment layer can be formed on the surface of the glass yarn (glass filament) after reducing organic matter that can increase the dielectric loss factor, thus facilitating the production of glass cloth with excellent dielectric properties. As a method for heating degreasing, known methods (heating components, heating media, heating mechanisms, heating devices, and heating parts, etc.) can be used.

[0059] As one of the heating degreasing steps, for example, a method of heating glass cloth at a temperature of 600 to 1600°C is known.

[0060] In the heat treatment step, by heating the glass cloth preform with a softening point of 900°C or higher within a temperature range of 600 to 1600°C, damage to the glass cloth is easily suppressed, and the dielectric loss factor of the glass cloth is easily reduced. From the viewpoint of suppressing the increase in the dielectric loss factor of the glass cloth over time, it is preferable to allow the silanol groups present on the glass surface to undergo sufficient dehydration and condensation within a range that will not adversely affect subsequent surface treatment steps. By reducing the amount of silanol groups on the glass surface to below a certain level, the adsorption of moisture from the air can be suppressed, resulting in the easy achievement of excellent dielectric properties and suppression of the increase in the dielectric loss factor over time.

[0061] From the viewpoint of obtaining superior dielectric properties and suppressing the increase in dielectric loss factor over time, the temperature for heat degreasing is preferably 700–1500°C, more preferably 800–1400°C, further preferably 900–1300°C, and even more preferably 1000–1200°C. If the heat degreasing temperature is above 600°C, it is easy to effectively remove the slurry and other substances adhering to the glass cloth blank, thus making it easier to produce glass cloth with excellent dielectric properties. If the heat degreasing temperature is below 1600°C, it is easy to suppress the devitrification of the glass, thereby preventing a decrease in the strength of the glass cloth.

[0062] The heating time is preferably less than 1 hour or less than 30 minutes, more preferably less than 15 minutes, and even more preferably less than 5 minutes. Heating the glass cloth at high temperature for a sufficient time easily induces a dehydration condensation reaction of the silanol groups on the glass surface. From the viewpoint of effectively removing sizing agents, the heating time can be, for example, more than 1 second, more than 5 seconds, more than 10 seconds, or more than 15 seconds.

[0063] When degreasing glass cloth by heating in a closed system, from the viewpoint of using a suitable heating method, it is preferable to place the glass cloth inside the heating furnace. Furthermore, from the viewpoint of maximizing storage space and heating range efficiency, it is preferable to store the glass cloth in a rolled-up state while heating. Moreover, from the viewpoint of improving the removal efficiency of organic matter and shortening the removal time of organic matter, it is preferable to heat the glass cloth while it is being transported within the heating furnace. The transport of the glass cloth can, for example, be carried out by a combination of a roll-up mechanism and a take-up mechanism.

[0064] When heating and degreasing glass cloth in an open system, from the viewpoint of ensuring the heated area, it is preferable to heat the glass cloth while it is being transported. The transport of the glass cloth can be carried out, for example, by a combination of a roll-up mechanism and a take-up mechanism.

[0065] The heating deoiling step is not limited to the above. As a further example of the heating deoiling step, a method is also known, for example, heating in a vacuum or a gas with a dew point of 15°C or lower, where the heating amount expressed as heating temperature (°C) × heating time (h) of 100°C or higher is 450 (°C·h) or higher (where the highest heating temperature is 100 to 600°C).

[0066] (Heating Component) As a heating component, for example, a heating furnace, an electric heater, a burner, etc. are considered, among which a gas-type single radiant tube burner or an electric heater is preferred. A plurality of different heating components can be combined.

[0067] From the viewpoint of efficiently removing organic matter adhering to the surface of the glass cloth, compared with a batch method of heating the glass cloth wound on the core at a specified ambient temperature, a continuous method of heating the glass cloth while it is continuously passing through the heating furnace is preferable. Even more preferable is a method that uses washing water with a low content of metal ions, such as reverse osmosis (RO) water or ion-exchange water, to continuously clean the glass cloth.

[0068] When the sodium ions adhering to the glass cloth exceed a specified amount, if the glass cloth is heated to remove oil at a temperature above 700°C, the tensile strength of the glass cloth may decrease due to devitrification of the quartz glass. To suppress devitrification, if the glass cloth is washed with water containing less than 20 ppm of sodium ions before heating and degreasing, the amount of sodium ions on the glass surface is easily reduced. In this case, even if heating and degreasing is performed at a temperature above 700°C, devitrification of the quartz glass is easily suppressed. By maintaining the strength of the glass cloth after heating and degreasing, wrinkles and / or damage to the glass cloth during surface treatment steps are easily suppressed.

[0069] From the viewpoint of better obtaining excellent dielectric properties and suppressing the increase of dielectric loss factor over time, the sodium ion content of the washing water can be less than 18 ppm, less than 15 ppm, less than 12 ppm, less than 10 ppm, or less than 7 ppm. The sodium ion content is preferably 0 ppm, but it can also exceed 0.

[0070] As a method for cleaning glass cloth with a sodium ion content of 20 ppm or less, any known cleaning method can be used as long as sodium ions on the glass surface can be removed. For example, methods using ultrasound (e.g., using an ultrasonic transducer), spraying (e.g., spraying with a high-pressure sprayer), or steam spraying are considered. From the viewpoint of cost-effective processing, a method of immersing the glass cloth in a tank containing cleaning water (water with a sodium ion content of 20 ppm or less), removing excess cleaning water with a squeeze roller, and then drying the glass cloth is preferred. In this case, the immersion time can be, for example, 2 seconds or more, 5 seconds or more, 10 seconds or more, 15 seconds or more but less than 120 seconds, 90 seconds or less, 60 seconds or less, or 45 seconds or less.

[0071] The method for producing water with a sodium ion content of 20 ppm or less can be a known method. For example, methods such as filtration using an RO membrane or deionization using an ion exchange resin can be considered. The "water with a sodium ion content of 20 ppm or less" may contain other liquid components (liquids other than water, etc.) without impairing the effects of the present invention.

[0072] From the viewpoint of easily promoting the dehydration condensation reaction of silanol groups on the glass surface, it is preferable to set the surrounding environment as dry as possible during the period from the time of heating and degreasing until the temperature of the glass cloth surface drops to below 100°C, that is, to reduce the moisture in the surrounding environment during heating and degreasing. Methods for reducing the moisture in the surrounding environment during heating and degreasing include, for example, introducing dry air into the heating furnace, creating a vacuum inside the furnace, and introducing an inert gas such as nitrogen into the furnace. When heating and degreasing is performed while the glass cloth is being transported, it is preferable to introduce an inert gas such as nitrogen into the furnace.

[0073] [Surface Treatment Step] In this step, the glass yarn is surface treated using a surface treatment liquid containing a specified surface treatment agent, particularly a specified silane coupling agent (which, in a given sample, is advantageous from the viewpoint of reducing the dielectric loss factor of the glass cloth). The silane coupling agent used in the method of the present invention is more hydrophobic than conventional silane coupling agents. Here, as mentioned above, the inventors of this invention understand that when the solvent of the surface treatment liquid contains water, there is a tendency for aggregates of the surface treatment agent to easily form, and when the solvent of the surface treatment liquid contains water, the frequency of white spots in the surface-treated glass cloth tends to increase.

[0074] Examples of methods for treating glass cloth with a surface treatment liquid (e.g., methods for coating glass cloth with a surface treatment liquid) include: (a) a method of conveying the glass cloth while immersing it in a surface treatment liquid accumulated in a bath (hereinafter referred to as the "immersion method"); (b) a method of directly coating the surface treatment liquid onto the glass cloth using a roller coater, a die coater, or a gravure coater. When using the immersion method, the immersion time of the glass cloth in the surface treatment liquid is preferably selected to be more than 0.5 seconds and less than 1 minute.

[0075] (Surface Treatment Liquid) The surface treatment liquid of the present invention is a surface treatment liquid containing a surface treatment agent, which can be used for surface treatment of glass cloth. The surface treatment agent has a molecular structure with a value of 15.0 or less obtained from the following formula (A): 1.10×MaxEStateIndex+14.6×MaxPartialCharge-0.0917×SPS+2.47×HallKierAlpha・・・(A)

[0076] Furthermore, it is preferable that the surface treatment agent contained in the above-mentioned surface treatment liquid contains the silane coupling agent shown in formula (1). In the surface treatment step, it is preferable to use a surface treatment liquid containing a surface treatment agent with a molecular weight of 200 or more to treat the glass yarn. In addition, the details of the surface treatment agent are as described in the above-mentioned item "Glass Cloth".

[0077] The inventors of this invention have discovered that, in a specified surface treatment solution, white spots on glass cloth can be suppressed, for example, by any one or more of the following methods (A) to (C): (A) preparing the surface treatment solution by adding an acidic aqueous solution to a hydrolyzed solution of a surface treatment agent; (B) controlling the temperature and / or pH value of the surface treatment solution and / or (C) filtering the surface treatment solution.

[0078] (A) Preparation of the surface treatment solution: As a conventional silane coupling agent, which has excellent water compatibility and dispersibility, it is prepared by gradually adding a small amount of hydrolyzed solution of the silane coupling agent (also referred to as the "preparation solution" in this invention) while stirring weakly acidic water with a pH of about 3 to 5. On the other hand, in the method of this invention, it is preferable to prepare the surface treatment solution by adding an acidic aqueous solution to the silane coupling agent. More preferably, an acidic aqueous solution is added to the obtained preparation solution containing the surface treatment agent. More specifically, a surfactant and a small amount of solvent (e.g., a 60% aqueous solution of acetic acid) for hydrolyzing the silane coupling agent are added to a diluted solution obtained by diluting the surface treatment agent with a small amount of methanol, thereby obtaining a hydrolyzed solution (preparation solution) of the surface treatment agent. Furthermore, the solvent in the preparative solution is added to hydrolyze the alkoxide groups of the silane coupling agent, and the amount of solvent added is preferably adjusted according to the amount of hydrolysis. Also, the surface treatment agent can be uniformly dispersed in the aqueous solution by gradually adding small amounts of an acidic aqueous solution (also referred to as the "mother liquor" in this invention) while stirring. In this case, it is easier to suppress the aggregation of the surface treatment solution. The acidic aqueous solution as the mother liquor is preferably a weak acid aqueous solution, for example, a weak acid aqueous solution with a pH value adjusted to 2.5 to 5.5, 3.0 to 5.0, 3.0 to 4.5, or 3.0 to 4.0. As a weak acid, for example, it is a carboxylic acid having the general formula RCOOH, where R is a substituted or unsubstituted alkyl group having 1 to 10 carbon atoms, and can be a straight-chain or branched alkyl group. Formic acid, acetic acid, and propionic acid are preferred as weak acids.

[0079] As a "small amount of solvent for hydrolyzing the silane coupling agent", the above-mentioned acidic aqueous solution used as the mother liquor can be used. Alternatively, as the mother liquor, a solvent for hydrolyzing the silane coupling agent (e.g., a 60% aqueous solution of acetic acid) can be used.

[0080] (Concentration of silane coupling agent) In this invention, the concentration of the silane coupling agent in the surface treatment agent is preferably in the range of 0.20 to 1.2% by mass. More preferably, it is 0.25 to 1.1% by mass, further preferably 0.30 to 1.0% by mass, even more preferably 0.33 to 0.9% by mass, and particularly preferably in the range of 0.35 to 0.7% by mass. If the concentration of the silane coupling agent is less than 1.2% by mass, the amount of silane coupling agent adhering to the surface of the glass cloth is reduced, and the dielectric loss factor of the glass cloth is reduced. If the concentration of the silane coupling agent is 0.2% by mass or more, the amount of silane coupling agent adhering to the surface of the glass cloth is increased, and the adhesion to the matrix resin is improved, thus helping to improve the heat resistance and other properties of the laminate.

[0081] As a surfactant, its composition and amount can be appropriately changed according to the type and amount of the surface treatment agent. Any of nonionic surfactants, anionic surfactants, cationic surfactants, and amphoteric surfactants can be used. Different types of surfactants can be used together.

[0082] Examples of nonionic surfactants include: glycerol fatty acid esters, sorbitan fatty acid esters, sucrose fatty acid esters, polyoxyethylene alkyl ethers, polyoxyethylene alkylphenyl ethers, polyoxyethylene polyoxypropylene glycol, fatty acid polyethylene glycol, fatty acid polyoxyethylene sorbitan, fatty acid alkylolamide, etc.

[0083] Examples of anionic surfactants include: fatty acid monocarboxylates, polyoxyethylene alkyl ether carboxylates, N-acylsarcosinate, N-acylglutamate, dialkylsulfonylsuccinate, alkyl sulfonates, α-olefin sulfonates, linear alkylbenzene sulfonates, alkylbenzene sulfonates, naphthalene sulfonate-formaldehyde condensate, alkylnaphthalene sulfonate, N-methyl-N-acyltaurate, alkyl sulfates, polyoxyethylene alkyl ether sulfates, oleic acid sulfates, alkyl phosphates, polyoxyethylene alkyl ether phosphates, and polyoxyethylene alkylbenzene ether phosphates.

[0084] Examples of cationic surfactants include: monoalkylamine salts, dialkylamine salts, trialkylamine salts, alkyltrimethylammonium chloride, alkylbenzylammonium chloride, etc.

[0085] Examples of amphoteric surfactants include: 2-alkyl-N-carboxymethyl-N-hydroxyethylimidazoline betaine, alkyl betaine, fatty aminopropyl betaine, alkyl diethyltriaminoacetic acid, alkylamine oxide, etc.

[0086] (Concentration of surfactant) In this invention, the concentration of the surfactant in the surface treatment solution is preferably in the range of 0.5 to 5.0% by mass relative to the aforementioned silane coupling agent. More preferably, it is 1.0 to 4.5% by mass, further preferably 1.5 to 4.0% by mass, further preferably 1.8 to 3.7% by mass, and even more preferably in the range of 2.0 to 3.5% by mass. If the concentration of the surfactant is less than 5.0% by mass relative to the aforementioned silane coupling agent, the amount of surfactant adhering to the surface of the glass cloth is reduced, and the CAF resistance of the laminate is improved. If the concentration of the surfactant is 0.5% by mass or more relative to the aforementioned silane coupling agent, the water dispersibility of the silane coupling agent is improved, thus making it easier to control the frequency of white spot generation to 10 spots / m².

[0087] (B) Temperature and / or pH control of the surface treatment solution From the viewpoint of inhibiting the aggregation of the surface treatment solution, it is preferable to have a step of controlling the temperature of the surface treatment solution during surface treatment. The temperature range is preferably controlled at 10–30°C, more preferably at 13–27°C, further preferably at 15–25°C, and even more preferably at 17–23°C.

[0088] Furthermore, during surface treatment, the pH value of the surface treatment solution may fluctuate due to trace amounts of alkali metals and other impurities contained in the glass cloth. From the viewpoint of suppressing the aggregation of the surface treatment solution, it is preferable to have a step of controlling the pH value of the surface treatment solution. During the surface treatment process, the pH value of the surface treatment solution is preferably controlled to be 2.5 to 5.5, more preferably 2.8 to 5.2, and even more preferably 3.0 to 5.0, 3.0 to 4.5, or 3.0 to 4.0. As a method for controlling the pH value within a specified range, examples include, for instance, introducing carbon dioxide into the surface treatment solution.

[0089] Temperature control and pH control of the surface treatment solution may be performed individually or both. From the viewpoint of appropriately suppressing flocculation of the surface treatment solution, it is preferable to perform both temperature control and pH control of the surface treatment solution.

[0090] Here, the concept of "temperature control of surface treatment solution" includes not only operations that raise and / or lower the temperature of the surface treatment solution, but also any of the following: operations that maintain the temperature of the surface treatment solution at a specified value, and operations that detect the temperature to confirm whether the temperature of the surface treatment solution is within a specified range. Similarly, the concept of "pH control of surface treatment solution" includes not only operations that raise and / or lower the pH value of the surface treatment solution, but also any of the following: operations that maintain the pH value of the surface treatment solution at a specified value, and operations that detect the pH value to determine whether the pH value of the surface treatment solution is within a specified range.

[0091] (C) Filtration of the surface treatment liquid From the viewpoint of reliably capturing the condensates in the surface treatment liquid, it is preferable to filter the surface treatment liquid during surface treatment. In this case, it is preferable to circulate the surface treatment liquid while capturing the condensates that may be generated in the surface treatment liquid by filtration.

[0092] From the viewpoint of improving the capture efficiency of flocculated material, it is preferable to perform filtration through multiple stages. For example, two-stage filtration is preferred, that is, after removing the flocculated material once with a filter with a coarser mesh, the surface treatment liquid is filtered again with a filter with a finer mesh than the first filter. This multi-stage filtration makes it easier to prevent filter clogging, and as a result, it is easier to avoid interruptions in the glass cloth manufacturing process.

[0093] (Drying Step) The surface treatment step may further include a step of drying the solvent contained in the surface treatment liquid after the glass yarn is coated with the surface treatment liquid (drying step). Through the drying step, the surface treatment agent is easily fixed to the surface of the glass yarn (the surface of the glass filament), and especially easily fixed to the surface of each individual glass yarn strand (the surface of each individual glass filament). Examples of methods for drying the solvent include, for instance, drying by heating, specifically, known methods such as drying by heating with hot air or electromagnetic waves.

[0094] As a drying temperature, from the viewpoint of ensuring sufficient reaction between the surface treatment agent and the glass, it is preferably 80°C or higher, and more preferably 90°C or higher. Furthermore, as a drying temperature, from the viewpoint of preventing the deterioration of the organic functional groups of the surface treatment agent, it is preferably 300°C or lower, and more preferably 180°C or lower.

[0095] [Fiber Opening Step] The manufacturing method of the present invention preferably includes a fiber opening step after the surface treatment step. Examples of fiber opening methods include: processing the glass cloth using water spray (high-pressure water fiber opening), a vibratory cleaner, ultrasonic water, and a rolling mill. During this fiber opening process, by reducing the tension applied to the glass cloth, the yarn width of the glass yarn is easily expanded, and surface treatment agents that are not chemically bonded to the glass surface are easily removed to some extent. To suppress the decrease in tensile strength of the glass cloth caused by the fiber opening process, it is preferable to implement measures such as low friction of the contact components during glass yarn weaving, optimization of the sizing agent, and high adhesion quantity.

[0096] [Cleaning Step] As a cleaning step, it is preferable to use a method that reduces the residue of surface treatment agents and modifiers that have not formed chemical bonds with the surface of the glass filaments. For example, a method of cleaning the glass yarn with an organic solvent can be used. By performing a cleaning step, even when using glass raw materials with a high silicon (Si) content, such as quartz glass, it is easy to adjust the difference between the dielectric loss factor and the bulk dielectric loss factor of the obtained glass cloth to a specified range.

[0097] As a cleaning step, in order to reduce the aforementioned residues that are not easily reduced by water, it is preferable to clean with an organic solvent with high hydrophobicity. Furthermore, it is preferable to clean with an organic solvent with high affinity for silane coupling agent residues containing hydroxyl groups. Examples of cleaning methods include known methods such as immersion and shower spray. Depending on the need, cleaning can be performed while heating or cooling. Preferably, the solvent remaining before drying is reduced by using a squeeze roller or similar device on the cleaned glass cloth in a manner that prevents the dissolved glass cloth residue from re-adhering. Suitable organic solvents, such as those with high hydrophobicity, include: saturated chain aliphatic hydrocarbons such as n-pentane, isopentane, n-hexane, isohexane, n-heptane, isoheptane, n-octane, isooctane, 2,2,4-trimethylpentane (isooctane), n-nonane, isononane, n-decane, isodecanane, 2,2,4,6,6-pentamethylheptane (isododecane); saturated cyclic aliphatic hydrocarbons such as cyclopentane, cyclohexane, methylcyclohexane, dimethylcyclohexane, and ethylcyclohexane; aromatic hydrocarbons such as benzene, toluene, xylene, ethylbenzene, diethylbenzene, trimethylbenzene, and triethylbenzene; and halogenated solvents such as chloroform, dichloromethane, and dichloroethane.

[0098] Examples of organic solvents that have a high affinity for surface treatment agents (e.g., silane coupling agents) include: alcohols such as methanol, ethanol, and butanol; ketones such as acetone and methyl ethyl ketone; ethers such as methyl ethyl ether and diethyl ether; amines such as N,N-dimethylformamide and N,N-dimethylacetamide; and dimethyl sulfoxide.

[0099] From the above perspective, it is easier to adjust the difference between the dielectric loss factor of the obtained glass cloth and the dielectric loss factor of the bulk material to a specified range. Aromatic hydrocarbons, alcohols or ketones are preferred, and methanol is even more preferred.

[0100] As a manufacturing method of the present invention, in order to reduce the amount of organic solvent after washing, it is preferable to include a step of drying the washed glass cloth (drying step after washing). From the viewpoint that it is easy to reduce the amount of organic solvent by drying, the boiling point of the organic solvent used in washing is preferably below 120°C. The drying of organic solvent can be carried out by known methods such as heating drying and air drying.

[0101] In the post-washing drying step, when heating is used to reduce organic solvents, from a safety point of view, it is preferable to use hot air drying with low-pressure steam or hot oil as the heat source. The drying temperature is preferably above the boiling point of the washing solvent, and from the viewpoint of inhibiting the deterioration of the silane coupling agent, it is preferably below 180°C.

[0102] [Any Step] The manufacturing method of the present invention may arbitrarily include other steps besides the steps described above. For example, the step of processing the glass cloth on the slit (slit processing step) can be cited.

[0103] (Inspection Step or Measurement Step) Another example is the step of inspecting the glass cloth for white spots. The manufacturing method of the present invention, by including this step, easily realizes the glass cloth of the present invention.

[0104] <<Prepreg>> The prepreg of the present invention comprises glass cloth, matrix resin, and inorganic filler. The prepreg of the present invention can use the aforementioned glass cloth as the glass cloth. Therefore, a prepreg with various excellent properties (e.g., a prepreg with fewer voids) is provided.

[0105] As the matrix resin, either a thermosetting resin or a thermoplastic resin can be used. Thermosetting resin and thermoplastic resin can be used together.

[0106] Examples of thermosetting resins include: a) an epoxy resin formed by reacting a compound having an epoxy group with a compound having at least one of an amino group, phenolic group, acid anhydride group, acehydrazine group, isocyanate group, cyanate group, and hydroxyl group that reacts with the epoxy group without a catalyst, or by adding a catalyst with reaction catalytic ability such as an imidazole compound, a tertiary amine compound, a urea compound, or a phosphorus compound; b) a free radical polymerization type resin formed by using a compound having at least one of an allyl group, a methacrylyl group, and an acrylyl group as a reaction initiator and then curing it; c) a cis-butenediamine tris(II) resin formed by reacting a compound having a cyanate group with a compound having a maleic anhydride group and then curing it. d) A thermosetting polyimide resin obtained by reacting a maleic diamide compound with an amine compound and then curing it; e) A benzo[a] resin obtained by crosslinking and curing a compound having a benzo[a] ring by heating polymerization; etc.

[0107] Examples of thermoplastic resins include: polyphenylene ether, modified polyphenylene ether, polyphenylene sulfide, polyurethane, polyetherurethane, polyarylate, aromatic polyamide, polyether ether ketone, thermoplastic polyimide, insoluble polyimide, polyamide-imide, LCP, polyester, fluoropolymer, etc.

[0108] The prepreg may contain inorganic fillers. Examples of inorganic fillers include: aluminum hydroxide, zirconium oxide, calcium carbonate, alumina, mica, aluminum carbonate, magnesium silicate, aluminum silicate, silicon dioxide, talc, short glass fibers, aluminum borate, and silicon carbide. Inorganic fillers may be used in combination with thermosetting resins.

[0109] <<Printed Wiring Board>> The printed wiring board of the present invention includes a prepreg. In particular, the printed wiring board of the present invention can be manufactured using the prepreg described above as a prepreg. This provides a printed wiring board with various excellent properties (e.g., a printed wiring board with excellent insulation reliability).

[0110] <<Integrated Circuits and Electronic Devices>> The integrated circuit of the present invention includes the printed wiring board described above. Furthermore, the electronic device of the present invention includes the printed wiring board described above. Therefore, integrated circuits and electronic devices with various excellent characteristics can be provided. Examples of electronic devices include information terminals such as smartphones; integrated circuits can be used to enhance the performance of electronic devices and to enable high-speed communication, such as 5G communication. [Example 1]

[0111] Hereinafter, examples and comparative examples will be given to illustrate the present invention. However, the present invention is not limited to the following examples. With respect to the examples and comparative examples, various manufacturing, measurement, and evaluation were performed by the following methods.

[0112] <<Determination and Evaluation Method>> [Calculation of Formula A] The formula (A) of the silane coupling agent is determined according to the operation described below. (1) MaxEStateIndex, MaxPartialCharge, SPS, and HallKierAlpha contained in Formula (A) are calculated using an open-source software called RDKit. Furthermore, the version of RDKit used is 2023.09.4. (2) The silane coupling agent represented by the following structure is converted from alkoxy or halogen (-Y) to hydroxyl (-OH) to prepare a silane coupling agent X4-n-Si(OH)n converted to a silanol structure. Silane coupling agent: X4-n-Si-Yn Each of X is an independent organic functional group, n is an integer between 1 and 3, and Y is an independent alkoxy or halogen group. (3) Convert the silane coupling agent converted to a silanol structure in operation (2) into a chemical structure in SMILES notation (simplified molecular input line entry system), which uses ASCII symbols, English letters, numbers, and symbols for stringing. (4) Create a MOL object from the SMILES notation structure created in operation (3) using the MolFromSmiles method of the rdkit.Chem.rdmolfiles module of RDKit. (5) The descriptor MaxEStateIndex is calculated from the MOL object created in operation (4) using the MaxEStateIndex method of the rdkit.Chem.EState.EState module of RDKit. (6) The descriptor MaxPartialCharge is calculated from the MOL object created in operation (4) using the MaxPartialCharge method of the rdkit.Chem.Descriptors module of RDKit. (7) The descriptor SPS is calculated for the MOL object created in operation (4) using the SPS method of the rdkit.Chem.SpacialScore module of RDKit. (8) The descriptor HallKierAlpha is calculated for the MOL object created in operation (4) using the HallKierAlpha method of the rdkit.Chem.GraphDescriptors module of RDKit.

[0113] (Linear sum of MaxEStateIndex, MaxPartialCharge, SPS, HallKierAlpha) Using the values ​​of MaxEStateIndex, MaxPartialCharge, SPS, and HallKierAlpha obtained through the above operations, calculate the linear sum of the values ​​of these descriptors according to the following formula: 1.10 × MaxEStateIndex + 14.6 × MaxPartialCharge - 0.0917 × SPS + 2.47 × HallKierAlpha

[0114] [Thickness] The thickness of the glass cloth is determined according to 7.10 of JIS R 3420. A micrometer is used, with the spindle rotating quietly and gently contacting the measuring surface parallel to it. The reading is taken after the ratchet emits three clicks. Furthermore, JIS R 3420 specifies the usual test methods for products containing long glass fibers and glass cloths using long glass fibers.

[0115] [Weight per unit area] The glass cloth is cut to a specified size to obtain a sample. The mass of the sample is divided by the area of ​​the sample to obtain the weight per unit area. Here, the glass cloth is cut to a size of 10 cm × 10 cm to obtain a sample, and its mass is measured to obtain the weight per unit area (g / m2).

[0116] [Converted Thickness] Glass cloth is a discontinuous planar body containing air and glass. Therefore, the converted thickness required for measurement using the resonance method is calculated by dividing the unit area weight of each glass cloth by the density of the glass. The calculation formula is as follows: Converted thickness (μm) = Unit area weight (g / m2) ÷ Density of glass (g / cm3).

[0117] [Dielectric Loss Factor] The dielectric loss factor of each glass cloth was determined according to IEC 62562. Specifically, glass cloth samples of the required size for measurement using each split-cylinder resonator were taken and kept in a constant temperature and humidity oven at 23°C and 50%RH for 8 hours under humidity control. Subsequently, the dielectric properties at 10 GHz were measured using a split-cylinder resonator (manufactured by EM Labs) and an impedance analyzer (manufactured by Agilent Technologies). The measurement was performed 5 times for each sample, and the average value was calculated. Furthermore, the dielectric loss factor of the glass cloth was calculated using the above-mentioned converted thickness as the thickness of each sample. In addition, regarding the bulk dielectric loss factor of the glass, a glass plate with the same composition as the glass cloth was prepared, and the bulk dielectric loss factor was calculated from the thickness of the glass plate using a split-cylinder resonator. Furthermore, IEC 62562 specifies a method for determining the dielectric properties of microwave strips made of precision ceramic materials primarily used as dielectric substrates in microwave circuits.

[0118] [Increase in Dielectric Loss Factor Over Time] Due to the presence of moisture in the storage environment, the dielectric loss factor of glass cloth can increase. Using a constant temperature and humidity chamber, the glass cloth was stored in a high-temperature and high-humidity environment (40℃, 90% relative humidity) for one week. The increase in dielectric loss factor before and after storage was calculated (dielectric loss factor after storage - dielectric loss factor before storage). (Conditions) Storage conditions: 40℃ × 90%RH Storage time: 1 week Dielectric loss factor: Measurement method described in the above [Dielectric Loss Factor] section.

[0119] [Loss on Ignition Value] The loss on ignition value of the glass cloth was calculated according to JIS R3420. Specifically, the glass cloth was dried at 110℃±5℃ for 60 minutes. Then, it was transferred to a desiccator and cooled at room temperature for 20 minutes, and the mass of the sample was measured to a unit of 0.1 mg (Amg). The dried sample was then heated at 625℃±20℃ for 20 minutes. Then, it was transferred to a desiccator and cooled for 20 minutes, and the mass of the sample was measured to a unit of 0.1 mg (Bmg). The loss on ignition value was calculated according to the following formula, rounded to four decimal places, and expressed as a third decimal place. Loss on ignition value (%) = [{A(mg)-B(mg)} / A(mg)]×100

[0120] [Average open fiber] Calculate the open fiber of the warp yarn of glass fabric by the following formula: Open fiber (%) = [warp width (μm) / {number of filament roots of warp × filament diameter of warp (μm)}] × 100. Also, the open fiber of the weft of the glass cloth is calculated by the following formula: the open fiber of the weft (%) = [width of the weft (μm) / {the number of filament roots of the weft × the diameter of the filament of the weft (μm)}] × 100.

[0121] Using the calculated open fiber (%) of the warp and the open fiber (%) of the weft, the average open fiber is calculated by the following formula: Average open fiber (%) = {open fiber (%) of the warp + open fiber (%) of the weft} / 2.

[0122] (Number of each filament for warp and weft yarns) In calculating the average open fiber, the number of each filament for warp and weft yarns is obtained by recourse to the observation of the cross-sectional image of the glass yarn. Specifically, a cross-sectional image of the glass yarn as a warp (or weft) is obtained, in which the number of filaments of the warp (or the weft) is determined. Similarly, the image acquisition of glass yarns, and the determination of filament number were repeated, and the average of the obtained five assays was taken as the filament number of warp (or weft) yarns.

[0123] (Wattage Width and Weft Width) When calculating the average open fiber, the warp width and weft width are obtained by means of the following method. First, five glass cloth samples with dimensions of 70 mm in the warp direction and 70 mm in the weft direction were cut from the glass cloth. The cut slices were observed from the vertical direction using a macroscope at a magnification of 100 times, respectively. For 1 sample, the yarn width of 250 warp (or weft) yarns was randomly determined, and the average value of the yarn width of the obtained 250 warp (or weft) yarns was obtained. The obtained average value is taken as the warp yarn width (or weft yarn width).

[0124] <<Examples of Manufacturing of Glass Cloth>> [Glass Cloth P] Warp and weft yarns containing glass yarns containing more than 99.9% by mass of SiO2 composition are used. Specifically, as warp and weft yarns, glass yarns with an average filament diameter of 5.0 μm, a filament number of 100 strands, and a peg number of 1.0 Z were used, respectively. Moreover, braiding densities of warp yarns of 66 strands / 25 mm and weft yarns of 68 strands / 25 mm, and 2000 m of glass cloth with a plain woven structure with a cloth width of 1300 mm were woven using an air-jet shuttleless loom. Further, the bulk dielectric loss factor at 10 GHz of the glass constituting the glass yarn used is 0.00020.

[0125] [Glass Cloth Q] Warp and weft yarns containing glass yarns containing more than 99.9% by mass of SiO2 composition are used. Specifically, as warp and weft yarns, glass yarns with an average filament diameter of 5.0 μm, a filament number of 200 strands, and a peg number of 1.0 Z were used, respectively. Also, braiding densities of warp yarns of 54 strands / 25 mm and weft yarns of 54 strands / 25 mm, and 2000 m of glass cloth with a plain woven structure with a cloth width of 1300 mm were woven using an air-jet shuttleless loom. Further, the bulk dielectric loss factor at 10 GHz of the glass constituting the glass yarn used is 0.00020.

[0126] [Glass Cloth R] Warp and weft yarns containing glass yarns containing more than 99.9% by mass of SiO2 composition are used. Specifically, as warp and weft yarns, glass yarns with an average filament diameter of 4.0 μm, a filament number of 50 strands, and a peg number of 1.0 Z were used, respectively. Moreover, braiding densities of 95 strands / 25 mm and 95 strands / 25 mm of warp yarns, and 2000 m of glass cloth with plain woven structure with cloth width of 1300 mm were woven using an air-jet shuttleless loom. Further, the bulk dielectric loss factor at 10 GHz of the glass constituting the glass yarn used is 0.00020.

[0127] <<Example of Preparation of Surface Treatment Liquid>> [Preparation Method I: Adding the mother liquor to the preparatory solution of the silane coupling agent] Prepare the surface treatment solution according to the following methods 1) to 6). 1) Weigh the silane coupling agent. 2) The silane coupling agent solution is prepared by mixing the same amount of methanol as the amount weighed in 1) above with the silane coupling agent weighed in 1) above. 3) Mix the silane coupling solution with a 0.8 mass % polyoxyethylene alkyl ether benchmarked by the mass of the silane coupling agent weighed in 1) above and stir for 1 minute. 4) To the solution of the silane coupling agent stirred in 3) above, an aqueous solution of acetic acid with a concentration of 60 mass percent is added in such a manner as to become 20 mass percent based on the mass of the silane coupling weighed in 1) above. Thereby, a preparatory solution containing a hydrolyzed silane coupling agent (hydrolyzed solution) was obtained. 5) Prepare the mother liquor of aqueous acetic acid solution (pH value = 3 to 4). Also, the prepared solution of the silane coupling agent obtained in the above 4) was stirred at room temperature of 20–25°C for 15 minutes. In this case, the above-mentioned mother liquor was added to the prepared solution of the stirred silane coupling agent, thereby dispersing the silane coupling agent. The addition amount and rate of addition of the mother liquor were set to the condition that the addition of the entire amount of the mother liquor was completed in 10 minutes. 6) After 5) above, a surface treatment solution was obtained by stirring the silane coupling agent solution for 2 hours at room temperature of 20–25°C.

[0128] [Preparation Method II: Preparative Solution with Silicon Coupling Agent Added to Mother Liquor] A surface treatment solution is prepared according to methods 1) to 6) below. 1) Weigh the silicon coupling agent. 2) Mix the same amount of methanol as weighed in 1) above with the silicon coupling agent weighed in 1) above to prepare a silicon coupling agent solution. 3) Mix the silicon coupling agent solution with 0.8% by mass of polyoxyethylene alkyl ether based on the mass of the silicon coupling agent weighed in 1) above, and stir for 1 minute. 4) Add a 60% by mass aqueous solution of acetic acid to the silicon coupling agent solution stirred in 3) above, to a concentration of 20% by mass based on the mass of the silicon coupling agent weighed in 1). This yields a preparative solution (hydrolyzed solution) containing hydrolyzed silicon coupling agent. 5) Prepare a mother liquor of acetic acid aqueous solution (pH = 3-4). Then, stir the prepared solution of the silane coupling agent obtained in 4) above at room temperature (20-25°C) for 15 minutes. At this time, add the stirred prepared solution of the silane coupling agent to the mother liquor to disperse the silane coupling agent. The amount and rate of addition of the mother liquor are set such that the entire amount of mother liquor is added within 10 minutes. 6) After 5) above, stir the silane coupling agent solution at room temperature (20-25°C) for 2 hours to obtain the surface treatment solution.

[0129] <<Examples and Comparative Examples>> [Example of Manufacturing Glass Cloth] (Example 1) Glass cloth P was washed with deionized water and then dried. This removed alkali metal ions and the like adhering to the surface of the glass cloth. Then, in a furnace with the set temperature adjusted to 700°C, the glass cloth was conveyed and heated for 30 seconds for degreasing (heating degreasing step).

[0130] As a silane coupling agent, 3,6-divinyl-1-(trimethoxysilyl)naphthalene (CAS NO: 2230040-75-0, molecular weight = 300.42, silane coupling agent A) represented by the following formula was used to prepare a surface treatment solution by the above preparation method I, with the concentration of the silane coupling agent in the surface treatment solution being 0.35% by mass. [Chemical 17]

[0131] The heated and degreased glass cloth is immersed in the obtained surface treatment liquid. Excess surface treatment liquid is squeezed out using an NBR rubber roller under a pressure of 0.3 MPa. Subsequently, the glass cloth is heated and dried at 130°C for 1 minute, thereby fixing the silane coupling agent onto the surface of the glass cloth.

[0132] In this embodiment, during the surface treatment of the glass cloth, temperature management (e.g., cooling) is performed so that the temperature of the surface treatment solution is in the range of 17 to 23°C. Furthermore, during the surface treatment of the glass cloth, carbon dioxide is introduced into the surface treatment solution so that the pH value of the surface treatment solution is in the range of 3.0 to 4.0.

[0133] Furthermore, in this embodiment, an HDCII filter (manufactured by Nihon Pall Corporation) is used to filter the surface treatment liquid used in the surface treatment of the glass cloth. That is, first, the surface treatment liquid is passed through a filter with a mesh size of 10 μm, and then the surface treatment liquid is passed through a filter with a mesh size of 4.5 μm. In this way, clumps that may exist in the surface treatment liquid are captured. The filtered surface treatment liquid is then used for the surface treatment of the glass cloth.

[0134] The surface-treated glass cloth was subjected to high-pressure fiber opening by applying a pressure of 3.5 kg / cm² using a spray nozzle. Subsequently, it was irradiated in water with an ultrasonic wave at a frequency of 25 kHz and an output of 0.40 W / cm² to reduce excess silane coupling agent physically adhering to the glass cloth while continuing the fiber opening process. Afterward, it was dried by heating at 130°C for 1 minute. Through these operations, 2000 m of surface-treated glass cloth was obtained.

[0135] (Example 2) Except for using methyl 2-acrylate [4-[2-(trimethoxysilyl)ethyl]phenyl]methyl ester (CAS NO: 141813-20-9, molecular weight = 310.42, silane coupling agent B) as the silane coupling agent, 2000 m of glass cloth was obtained by the same method as in Example 1. [Chemical 18]

[0136] (Example 3) Except for using 4-(trimethoxysilyl)phenyl 2-acrylate (CAS NO: 220369-00-6, molecular weight = 268.34, silane coupling agent C) as the silane coupling agent, 2000 m of glass cloth was obtained by the same method as in Example 1. [Chemical 19]

[0137] (Example 4) Except for using N-vinyl-N-(2-epoxyethylenemethoxy)-3-(trimethoxysilyl)-1-propylamine (CAS NO: 142177-48-8, molecular weight = 277.39, silane coupling agent D) as the silane coupling agent, 2000 m of glass cloth was obtained by the same method as in Example 1. [Chemical 20]

[0138] (Example 5) Except for using 1-vinyl-4-[3-(trimethoxysilyl)propoxy]benzene (CAS NO: 149738-31-8, molecular weight = 282.41, silane coupling agent E) as the silane coupling agent, a surface-treated glass cloth of 2000 m was obtained by the same method as in Example 1. [Chemical 21]

[0139] (Example 6) Except for using 4-[2-(trimethoxysilyl)ethyl]aniline (CAS NO: 56926-97-7, molecular weight = 241.36, silane coupling agent F) as the silane coupling agent, a surface-treated glass cloth of 2000 m was obtained by the same method as in Example 1. [Chemical 22]

[0140] (Example 7) Except for using [bicyclo[2.2.1]hept-5-en-2-yl]triethoxysilane (CAS NO: 18401-43-9, molecular weight = 256.41, silane coupling agent G) as the silane coupling agent, a surface-treated glass cloth of 2000 m was obtained by the same method as in Example 1. [Chemical 23]

[0141] (Example 8) Except for using glass cloth Q instead of glass cloth P and setting the concentration of silane coupling agent in the surface treatment solution to 0.25% by mass, 2000 m of glass cloth was obtained by the same method as in Example 1.

[0142] (Example 9) Except for using glass cloth R instead of glass cloth P and setting the concentration of silane coupling agent in the surface treatment solution to 0.25% by mass, 2000 m of glass cloth was obtained by the same method as in Example 1.

[0143] (Example 10) Except for the aspect of performing surface treatment without filtering the surface treatment liquid, 2000 m of glass cloth was obtained by the same method as in Example 1.

[0144] (Example 11) Except for the fact that the surface treatment liquid is not cooled even when the temperature exceeds 23°C and carbon dioxide is not introduced even when the pH value exceeds 4.0, 2000 m of glass cloth was obtained by the same method as in Example 1.

[0145] (Example 12) Except for setting the concentration of silane coupling agent in the surface treatment solution to 0.75% by mass, 2000 m of glass cloth was obtained by the same method as in Example 1.

[0146] (Example 13) Except for setting the concentration of silane coupling agent in the surface treatment solution to 1.1% by mass, 2000 m of glass cloth was obtained by the same method as in Example 1.

[0147] (Comparative Example 1) Except for the use of 3-(trimethoxysilyl)propyl methacrylate (CAS NO: 2530-85-0, molecular weight = 248.35, silane coupling agent H) as a silane coupling agent, 2000 m of surface-treated glass cloth was obtained by the same method as in Example 1.

[0148] (Comparative Example 2) Except for the use of 5-hexenyltrimethoxysilane (CAS NO: 58751-56-7, molecular weight = 204.34, silane coupling agent I) as a silane coupling agent, 2000 m of surface-treated glass cloth was obtained by the same method as in Example 1.

[0149] (Example 14) Except for the aspects of preparing the surface treatment liquid according to the preparation method II described above, not filtering the surface treatment liquid and performing surface treatment on the glass cloth, not cooling the surface treatment liquid even if the temperature of the surface treatment liquid exceeds 23°C, and not introducing carbon dioxide even if the pH value exceeds 4.0, 2000 m of glass cloth was obtained by the same method as in Example 1.

[0150] [Frequency of White Spot Occurrence] On a roll-to-roll inspection table, while applying a tension of 100 N / 1300 mm to the glass cloth and illuminating it with a halogen lamp, the number of white spots generated on a 2000 m length of glass cloth is counted. Furthermore, based on the inspected area and the number of white spots found, the frequency of white spot occurrence is calculated using the following formula: Frequency of white spot occurrence (number / m²) = Number of white spots / {Width of glass cloth (m) × Length of inspected glass cloth (m)}.

[0151] Figure 1 is a photograph used to illustrate the "white spot" of the present invention. In Figure 1(a), a photograph shows a region without a white spot, and in Figure 1(b), a photograph shows a region with a white spot P. In the present invention, a "white spot" is defined as a defect in which a white outline is observed under UV light, and the area enclosed by the outline (including the outline area) is 0.8 cm² or more. Here, the outline is, for example, circular. Furthermore, the area enclosed by the outline is calculated using known image analysis software.

[0152] [Example 1 of Prepreg Manufacturing] In this Example 1, polyphenylene ether resin was used as the raw material. Specifically, 45 parts by weight of polyphenylene ether (manufactured by SABIC, Noryl SA9000), 10 parts by weight of triallyl isocyanurate, 45 parts by weight of toluene, and 0.6 parts by weight of 1,3-bis(tributylisopropylbenzene) were added to a stainless steel container and stirred at room temperature for 1 hour. A varnish was thus prepared. The glass cloths obtained in Examples 1-3, 5, 7, 8-14 and Comparative Examples 1 and 2 were impregnated with the prepared varnish and dried at 130°C for 1 minute to obtain a prepreg.

[0153] [Prepreg Manufacturing Example 2] In this Manufacturing Example 2, epoxy resin was used as the raw material. Specifically, 80 parts by weight of low-brominated bisphenol A type epoxy resin, 20 parts by weight of cresol phenolic varnish type epoxy resin, 2 parts by weight of dicyandiamide, 0.2 parts by weight of 2-ethyl-4-methylimidazolium, and 100 parts by weight of 2-methoxy-ethanol were mixed to prepare a varnish. After impregnating the glass cloth obtained in Examples 4 and 6 with the prepared varnish, it was dried at 130°C for 7 minutes to obtain the prepreg.

[0154] [Example of manufacturing polyphenylene ether resin substrate] A sample of the obtained prepreg was taken in the shape of 20 cm × 20 cm. Eight samples were stacked, and then copper foil with a thickness of 12 μm was stacked on the top and bottom sections. The resin substrate was then produced by heating and pressurizing at 200°C and 40 kg / cm2 for 120 minutes.

[0155] [Example of manufacturing epoxy resin substrate] A sample of the obtained prepreg was taken in the shape of 20 cm × 20 cm. Eight samples were stacked, and then copper foil with a thickness of 12 μm was stacked on the top and bottom sections. The resin substrate was then produced by heating and pressurizing at 195°C and 40 kg / cm2 for 120 minutes.

[0156] [Solder Heat Resistance] The top and bottom copper foil sections were removed from the resin substrate to obtain a laminate. Ten laminates of 5 cm × 5 cm were cut from the obtained laminate. The laminates were then heated at 133°C for 24 hours and subjected to water absorption in a pressure cooker. The absorbed laminates were then immersed in a solder bath at 288°C for 20 seconds. The 10 laminate samples were then visually inspected for any bulging caused by peeling at the glass cloth / resin interface.

[0157] Laminate samples with bulging caused by peeling at the glass cloth / resin interface are deemed "unacceptable," and the number of such unacceptable laminate samples is recorded. The fewer glass cloth samples recorded in the table, the better the heat resistance.

[0158] Regarding the embodiments and comparative examples, the manufacturing conditions and evaluation results are shown in the table below. Furthermore, using the glass cloth of the embodiments, prepregs, printed wiring boards (resin substrates), integrated circuits, and electronic devices can be manufactured by conventional methods.

[0159] [Table 1] Table 1. Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 Example 8 Fiberglass cloth P P P P P P P Q Heating and degreasing steps temperature - 700 700 700 700 700 700 700 700 time - 30 sec 30 sec 30 sec 30 sec 30 sec 30 sec 30 sec 30 sec Surface treatment steps Silane coupling agent - A B C D E F G A Molecular weight of silane coupling agents - 300.42 310.42 268.34 277.39 282.41 241.36 256.41 300.42 Preparation method of surface treatment liquid * - I I I I I I I I Filtration of surface treatment liquid - Implementation Implementation Implementation Implementation Implementation Implementation Implementation Implementation Temperature and pH management of surface treatment solutions - Implementation Implementation Implementation Implementation Implementation Implementation Implementation Implementation concentration quality% 0.35 0.35 0.35 0.35 0.35 0.35 0.35 0.25 MaxEStateIndex - 9.53 10.85 10.78 8.78 8.77 8.76 9.06 9.53 MaxPartialCharge - 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 SPS - 11.5000 11.0556 10.8667 20.0667 11.1875 11.6154 41.9091 11.5000 HallKierAlpha - -1.72 -1.47 -1.47 -0.44 -1.14 -0.88 -0.16 -1.72 Calculated value of formula (A) - 12.9 14.5 14.9 13.9 13.0 13.6 13.0 12.9 Glass cloth properties thickness μm 34 34 34 34 34 34 34 47 Weight per unit area g / m 2 25.6 25.7 25.5 25.6 25.5 25.5 25.5 40.2 Average fiber opening degree % 58 58 58 58 58 58 58 57 Loss on ignition (After surface treatment) % 0.06 0.06 0.06 0.06 0.06 0.06 0.06 0.04 Frequency of white spot occurrence pcs / m 2 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 Dielectric loss factor of glass cloth @ 10 GHz - 0.00035 0.00038 0.00039 0.00037 0.00035 0.00036 0.00035 0.00036 The increase in dielectric loss factor over time (×10) -5 ) - 6.2 9.6 9.8 8.4 6.4 7.7 6.3 6.2 Solder heat resistance 0 0 0 0 0 0 0 0 *: I. Add mother liquor to the preparative solution of silane coupling agent. II. Add the preparative solution of silane coupling agent to the mother liquor.

[0160] [Table 2] Table 2. Example 9 Example 10 Example 11 Example 12 Example 13 Comparative Example 1 Comparative Example 2 Example 14 Fiberglass cloth R P P P P P P P Heating and degreasing steps temperature - 700 700 700 700 700 700 700 700 time - 30 sec 30 sec 30 sec 30 sec 30 sec 30 sec 30 sec 30 sec Surface treatment steps Silane coupling agent - A A A A A H I A Molecular weight of silane coupling agents - 300.42 300.42 300.42 300.42 300.42 248.35 204.34 300.42 Preparation method of surface treatment liquid * - I I I I I I I II Filtration of surface treatment liquid - Implementation Not implemented Implementation Implementation Implementation Implementation Implementation Not implemented Temperature and pH management of surface treatment solutions - Implementation Implementation Not implemented Implementation Implementation Implementation Implementation Not implemented concentration quality% 0.25 0.35 0.35 0.75 1.1 0.35 0.35 0.35 MaxEStateIndex - 9.53 9.53 9.53 9.53 9.53 10.77 8.54 9.53 MaxPartialCharge - 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 SPS - 11.5000 11.5000 11.5000 11.5000 11.5000 11.0769 11.5000 11.5000 HallKierAlpha - -1.72 -1.72 -1.72 -1.72 -1.72 -0.69 -0.16 -1.72 Calculated value of formula (A) - 12.9 12.9 12.9 12.9 12.9 16.3 15.1 12.9 Glass cloth properties thickness μm 15 34 34 34 34 34 34 34 Weight per unit area g / m 2 10.5 25.5 25.5 25.5 25.5 25.4 25.4 25.4 Average fiber opening degree % 60 58 58 58 58 58 58 58 Loss on ignition (After surface treatment) % 0.04 0.06 0.06 0.14 0.18 0.06 0.06 0.06 Frequency of white spot occurrence pcs / m 2 0.01 3 1 1 3 0.01 0.01 20 Dielectric loss factor of glass cloth @ 10 GHz - 0.00036 0.00035 0.00035 0.00045 0.00049 0.00043 0.00040 0.00035 The increase in dielectric loss factor over time (×10) -5 ) - 6.2 6.2 6.2 6.2 6.2 14.2 10.1 6.2 Solder heat resistance 0 3 2 2 3 0 0 10 *: I. Add mother liquor to the preparative solution of silane coupling agent. II. Add the preparative solution of silane coupling agent to the mother liquor.

[0161] According to Examples 1-14, a glass cloth capable of achieving the following: excellent dielectric properties, suppression of the increase in dielectric loss factor over time, and excellent solder heat resistance of the resin substrate made using the glass cloth. On the other hand, Comparative Examples 1-2 failed to suppress the increase in dielectric loss factor over time. [Industrial Applicability]

[0162] This invention can be used in fields related to glass cloth, printed wiring boards (especially printed wiring boards for high-speed communication), etc. [Simplified Explanation of the Diagram]

[0009] Figure 1(a) and (b) are diagrams used to illustrate the white dots.

Claims

1. A glass cloth comprising glass yarn containing a plurality of glass filaments as warp and weft yarns, wherein the glass cloth has a surface treatment agent on its surface, the surface treatment agent comprising a silane coupling agent having a molecular structure having a value of 15.0 or less obtained from the following formula (A): 1.10×MaxEStateIndex+14.6×MaxPartialCharge-0.0917×SPS+2.47×HallKierAlpha・・・(A) 2. The glass cloth as requested in item 1, wherein the number of white spots is less than 10 per m2.

3. The glass cloth as requested in item 1 or 2, wherein the silicon (Si) content in the glass yarn is 95.0 to 100% by mass, converted to silicon dioxide (SiO2).

4. The glass cloth of claim 1 or 2, wherein the silane coupling agent contains a silane coupling agent represented by the following general formula (1): X4-n-Si-Yn・・・(1) (in formula (1), each X is an organic functional group having at least one of an epoxy group, an amino group, and an unsaturated double bond group having free radical reactivity, each Y is an alkoxy group, and n is an integer from 1 to 3).

5. The glass cloth of claim 4, wherein X in the above general formula (1) contains at least one group selected from the group consisting of epoxy, amino, aromatic vinyl, acrylonitrile, and methacryl.

6. The glass cloth as requested in item 1 or 2, wherein the dielectric loss factor of the glass cloth at 10 GHz is less than 0.

002.

7. The glass cloth as requested in item 1 or 2, wherein the loss on ignition is in the range of 0.01 to 0.3% by mass.

8. The glass cloth as requested in item 1 or 2, wherein the value obtained from the above formula (A) is 14.4 or less.

9. The glass cloth as requested in item 1 or 2, wherein the value obtained from the above formula (A) is 13.8 or less.

10. The glass cloth as requested in item 1 or 2, wherein the value obtained from the above formula (A) is 13.5 or less.

11. For glass cloth as requested in item 1 or 2, the number of white spots is less than 4 per m2.

12. For glass cloth as requested in item 1 or 2, the number of white spots is less than 2 per m2.

13. For the glass cloth requested in item 1 or 2, the number of white spots is less than 0.1 per m2.

14. For glass cloth as requested in item 1 or 2, the number of white spots is less than 0.05 per m2.

15. The glass cloth of claim 1 or 2, wherein the molecular weight of the silane coupling agent is in the range of 250 to 1000.

16. The glass cloth of claim 1 or 2, wherein the molecular weight of the silane coupling agent is in the range of 300 to 750.

17. The glass cloth of claim 1 or 2, wherein the molecular weight of the silane coupling agent is in the range of 350 to 700.

18. The glass cloth requested in item 1 or 2 is for use with printed wiring boards.

19. A prepreg comprising glass cloth, matrix resin, and inorganic filler as claimed in claim 1 or 2.

20. A printed wiring board comprising a prepreg as claimed in claim 19.

21. An integrated circuit comprising a printed wiring board as claimed in claim 20.

22. An electronic machine comprising a printed wiring board as claimed in claim 20.

23. A method for manufacturing glass cloth, the method comprising: The step of weaving glass yarn containing multiple glass filaments as warp and weft yarns to obtain glass cloth; The process involves degreasing the glass cloth and then surface treating it with a surface treatment liquid containing a surface treatment agent. The surface treatment agent contains a silane coupling agent having a molecular structure with a value of 15.0 or less obtained from the following formula (A): 1.10×MaxEStateIndex+14.6×MaxPartialCharge-0.0917×SPS+2.47×HallKierAlpha・・・(A) 24. The method of manufacturing glass cloth according to claim 23, wherein the silane coupling agent contains the following general formula (1): X4-n-Si-Yn・・・(1) (in formula (1), each X is an organic functional group having at least one of an epoxy group, an amino group, and an unsaturated double bond group having free radical reactivity, each Y is an alkoxy group, and n is an integer from 1 to 3).

25. The method for manufacturing glass cloth as claimed in claim 23 or 24, wherein the surface treatment liquid is prepared by adding an acidic aqueous solution to the hydrolysis solution of the silane coupling agent.

26. A method for manufacturing glass cloth as claimed in claim 23 or 24, wherein the surface treatment steps described above include: Control the temperature and pH value of the above surface treatment solution; and filter the above surface treatment solution.

27. The method of manufacturing the glass cloth as described in claim 23 or 24 further includes: Following the surface treatment steps described above, the glass cloth is then subjected to a fiber-opening process.

28. The method for manufacturing the glass cloth as described in claim 23 or 24 further includes: After the above surface treatment steps, check for white spots.

29. A surface treatment liquid comprising a surface treatment agent containing a silane coupling agent, wherein the silane coupling agent has a molecular structure having a value of 15.0 or less obtained from the following formula (A): 1.10×MaxEStateIndex+14.6×MaxPartialCharge-0.0917×SPS+2.47×HallKierAlpha・・・(A) 30. The surface treatment solution of claim 29, wherein the surface treatment solution contains a silane coupling agent in the range of 0.20% to 1.2% by mass based on the total mass of the surface treatment solution, the pH value of the surface treatment solution is in the range of 2.5 to 5.5, and the surface treatment solution contains a surfactant in the range of 0.5% to 5.0% by mass based on the total mass of the silane coupling agent.

31. The surface treatment liquid of claim 29 or 30, wherein the silane coupling agent contains the following general formula (1): X4-n-Si-Yn・・・(1) (in formula (1), each X is an organic functional group having at least one of an epoxy group, an amino group, and an unsaturated double bond group having free radical reactivity, each Y is an alkoxy group, and n is an integer from 1 to 3).

32. The surface treatment liquid as claimed in claim 29 or 30, wherein the value obtained from the above formula (A) is 14.4 or less.

33. The surface treatment liquid as requested in item 29 or 30, wherein the value obtained from formula (A) above is 13.8 or less.

34. The surface treatment liquid as claimed in claim 29 or 30, wherein the value obtained from the above formula (A) is 13.5 or less.

35. The surface treatment solution as claimed in claim 29 or 30, wherein the pH value of the surface treatment solution is in the range of 3.0 to 5.

0.

36. The surface treatment solution as claimed in claim 29 or 30, wherein the pH value of the surface treatment solution is in the range of 3.0 to 4.

0.

37. The surface treatment liquid of claim 29 or 30, wherein the surface treatment liquid contains a surfactant in the range of 1.0 to 4.5% by mass based on the total mass of the silane coupling agent.

38. The surface treatment liquid of claim 29 or 30, wherein the surface treatment liquid contains a surfactant in the range of 1.5 to 4.0% by mass based on the total mass of the silane coupling agent.

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